[wp-hackers] HyperDB seems to be causing an unusual number of PING to the database

[dave morris]

I am using HyperDB with WordPress 3.0.1, and I have a MySQL network
sniffer setup to log all database traffic. I have a master write db
server and two slave read servers right now.

While analyzing some of the log files the other day, I noticed an
unusual number of PING and CONNECT requests, and I'm wondering if this
may be caused by my HyperDB configuration. Here is an example from the
sniffer logs of a 10 minute period of time. There are 600K+ PING
requests:

# Profile
# Rank Query ID           Response time    Calls  R/Call   Apdx V/M
Item
# ==== ================== ================ ====== ======== ==== =====
====
#    1 0x5D51E5F01B88B79E  1730.0760 78.0%  15216   0.1137 1.00 32...
ADMIN CONNECT
#    2 0x04FE01C5B31FD305    74.5528  3.4% 604880   0.0001 1.00  0.67
ADMIN PING
#    3 0x23C8A0F1ED72D23D    57.2139  2.6%  17758   0.0032 1.00  0.02
SELECT wp_?_posts
#    4 0xE0E902FB71244C1E    41.6918  1.9%   2540   0.0164 1.00  0.09
SELECT wp_?_posts
#    5 0xDAADAC0539F80EE6    27.2083  1.2% 175902   0.0002 1.00  0.00
SELECT wp_sitemeta
...

This happened during a high traffic day, but it's still making me
curious whether I should modify my HyperDB configuration. I have
tcp_responsiveness_check on, and persistent off right now. Could this
be causing the large number of PINGs and CONNECTs?

If I turn on persistent connections and turn off
tcp_responsiveness_check, what other implications will that have on my
current setup?

Thanks for your help,
Dave